"This tutorial describes how to install and configure OpenSSH so that it will allow chrooted sessions for users. With this setup, you can give your users shell access without having to fear that they can see your whole system. Your users will be jailed in a specific directory which they will not be able to break out of."

I read on the net that "chroot" is never a real secure way to jail someone in. With some C-skills one should be able to break out a chroot environment in every situation. The most simple ways to do this are easy to prevail, though.